The present invention relates generally to methods for producing ultra-fine particles of amorphous elemental and compound materials in amorphous or crystalline form.
Small particle size material has a large surface to volume ratio. For this reason, chemical processes often work better by using small size particles for feed stock material. Small particle size is also important for pharmaceuticals and nutritional supplements, which are taken up by the body more easily and effectively when in small particle sizes.
One such material with many industrial uses is carbon black, which is an amorphous form of pure carbon. Carbon black is useful as a carbon feed stock for chemical processes, e.g. in plastic production, in compounding of rubber, and in the production of inks and pigments. Typically, carbon black is produced by burning acetylene and other organic fuels under low oxygen conditions. This is energy intensive and creates gas by-products that are undesirable.
There is a growing interest in recovery of carbon from scrap material so it can be recycled in useful ways. One such source of carbon is from pyrolyzed scrap vehicle tires. Millions of kilograms of char (essentially pure carbon) are potentially available from tire xe2x80x9cwaste.xe2x80x9d Chars having different properties and characteristics can be made consistently by changing process parameters, such as pyrolysis temperature, heating rate, pyrolysis time, the rotating speed of the reactor, and the presence or absence of additives.
Such pyrolytic char particles typically range in size from about one micron to over one millimeter. Carbon particles of this size range are too large for use in compounding of tire tread rubber, plastics and other materials or for use as pigment in printers. The char must therefore be made into particle sizes of about one micron or less in order to generate carbon that can be used to produce new products. For most large volume uses, such fine particle sizes are desirable or required. Since thousands of tons of fine carbon particles are used in various industries, machines that can process large amounts of material are required.
Other hard materials that are crystalline or amorphous in form are generally difficult to grind into smaller particle sizes that would be useful for uses such as food processing or nutritional supplements. Such materials include crystals of organic molecules containing minerals and non-mineral containing organic compounds. For most of these materials a particle size of less than about 50 microns is highly desirable.
The invention provides methods for producing useful, small particle forms of both elemental and compounded materials using resonance disintegration. The materials may be in either amorphous or crystalline form. In most cases, a fine, flowable powder is produced.
In one aspect, the invention provides a continuous flow method of reducing the mean particle size of a particulate carbon material that consists of at least about 90% carbon by weight. The method includes entraining the carbon material in a gas flow through an inlet of a housing, subjecting the flowing carbon material to a plurality of rapid alternating pressure increases and decreases within the housing, disintegrating the flowing carbon material with the pressure increases and decreases, thereby reducing the mean particle size of the carbon material, and discharging the disintegrated carbon material though an outlet of the housing. The carbon material can comprise an amorphous form of carbon, such as carbon black or pyrolyzed carbon char, or a crystallized form of carbon, such as graphite. Processing as recited above appears to produce a more hydrophilic form of carbon particle. In one embodiment, the method can include coating the carbon particles with an adherent material, such as oil, while the particles are flowing though the housing.
In embodiments where the amorphous form of carbon is carbon char, the median volume distribution of the sizes of the discharged carbon particles is in a range of about 1.6-2.7 microns when dispersed in isopropanol. Such discharged carbon particles when dispersed in isopropanol are characterized by at least about 93% of the particles being below about 30 microns in size, by about 60-90% of the particles being below about 5 microns in size, and by about 5.3-16% of the particles being below about 1 micron in size. When dispersed in water, the median volume distribution of the sizes of the discharged carbon particles made from carbon char is less than about one micron, and preferably about 0.52-0.88 microns or less. When dispersed in water, the discharged carbon particles made from char are characterized by essentially 100% of the particles being below about 30 microns in size, by about 75% of the particles being smaller that about 5 microns in size, and by about 46-51% of the particles by volume being below about 1 micron in size.
When the elemental amorphous material is carbon black, the median volume distribution of the sizes of the discharged carbon particles is less than about 3 microns, and preferably from about 0.52-2.7 microns in size. The median volume distribution of the discharged carbon particles made from carbon black is about 0.52 microns when dispersed in water. The discharged carbon particles when dispersed in water are characterized by essentially 100% of the particles being about 5 microns or less, and by about 90% of the particles being about 1 micron or less.
The invention, in yet another aspect, provides a powdered form of amorphous carbon, consisting essentially of particles that when dispersed in water are characterized by essentially 100% of the particles having a size of about 5 microns or less, and by about 90% of the volume of the particles having a size of about 1 micron or less. The particles can be further characterized by having a median volume distribution of about 0.52 microns.
In still another aspect, the invention provides a powdered form of carbon char, consisting essentially of particles that when dispersed in water are characterized by essentially 100% of the particles being about 30 microns or less. The powdered carbon char particles can be further characterized by about 75% of the particles by volume being about 5 microns or less in size, and by at least about 46% of the particles by volume being about one microns or less in size
In another aspect, the invention provides a continuous flow method of reducing the particle size of crystals of an organic molecule, wherein the initial particle size of the crystals is at least about +80 mesh. The method steps include: entraining the crystals in a gas flow through an inlet into a housing; subjecting the crystals to a plurality of pressure increases and decreases while flowing through the housing; disintegrating the flowing crystals with the pressure increases and decreases, thereby reducing the mean particle size of the crystals; and discharging the disintegrated crystals though an outlet of the housing, wherein substantially all the discharged crystals have a particle size that is about xe2x88x92270 mesh. In some embodiments, wherein substantially all of the discharged crystals have a particle size that is less than about 20 microns. In other embodiments, most of the discharged crystals have a particle size that is less than about 4 microns.
The organic molecule can contain a mineral In certain features, the organic molecule is selected from the group consisting of calcium citrate, magnesium citrate and methylsulfonylmethane.
In other embodiments wherein the organic molecule does not contain a mineral. Such organic molecule may be selected from the group consisting of creatine monohydrate, ipriflavone, and zein.
The invention provides many advantages. The ultrafine carbon particles produced according to the invention have a very small size distribution, even smaller than carbon black, when dispersed in water. The small particle size and the easy dispersion in water makes these carbon particles particularly useful for making inks and dyes for use in ink jet and other types of printers. The fine particle size carbon material is also very useful as a feed-stock for compounding tread rubber, plastics, and the like.
The organic materials that are reduced in size are more easily put into solution than other forms of such compounds. This is advantageous when using these substances in food processing or as dietary food supplements. The smaller particle size enables these materials to be more readily absorbed in the body.
Other objectives and advantages of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.